Magnetism Flashcards
Lorentz Force
F^ = qv^ x B^
Direction of the Lorentz Force
perpendicular to both v^ and B^
Total Magnetic Force on a Current Element
F^ = (qv^ x B^)nAL = IL^ x B^
Motion in a Magnetic Field
- magnetic force is always perpendicular to the velocity of the particle
- speed does not change, kinetic energy is constant
- in a uniform magnetic field, motion is always circular
Radius of the Motion of a Particle in a Magnetic Field
Equation
r = mv/Bq
Cyclotron Frequency
Equation
f = qB / 2πm
Cyclotron
Description
- accelerates particles in a limited amount of space
- alternating voltage applied between two ‘Dees’
- particle is accelerated in a spiral
- when it leaves at maximum radius its kinetic energy can be very large
Cyclotron - Kinetic Energy
KE = mv² / 2 = q²B²r²/2m
Describe the Magnetic Field of a Solenoid
- a solenoid is a wire wound into a helix of closely spaced coils
- it produces a strong, uniform magnetic field inside the coil
- acts like a magnet
Magnetic Field Due to a Current Loop
B = μ0I / 2R
Magnetic Field Due to a Long Wire
B = μ0I/4πR (sinθ2 - sinθ1)
Magnetic Field of an Infinitely Long Wire
B = μ0I/2πR
Force per unit length exerted by a wire on a wire segment
dF1,2 / dl2 = μ0I1I2/2πR
Magnetic Flux Equation (Integral)
Φ = ∫ B.n^ dA
Weber Definition
- unit of magnetic flux
- defined as magnetic flux density multiplied by area
Magnetic Flux Equation
Φ = BAcosθ
where θ is the angle between the plane of the are and the plane of the field
Faraday’s Law
-for a surface bounded by a conducting material, a change in magnetic flux induces an electromagnetic force in the opposite direction to the movement of the charge
ε = - dΦ/dt
